Method and apparatus for electrolytic treatment of slide fasteners



Oct. 30, 1951 c, c c 2,572,838

METHOD AND APPARATUS FOR ELECTROLYTIC TREATMENT OF SLIDE FASTENERS Filed April 24, 1946 14 15 l g i6. 1- l J J 4 T T 4| 6 ,4 I 4 SC I I" I 6 F INVENTOR. 1 Charles C. Calm 6. I T Y Z/ AZAMH %RNEY5 Patented Oct. 30, 1951 METHOD AND APPARATUS FOR ELECTRO- LYTIC TREATMENT OF SLIDE FASTENERS Charles C. Cohn, Elkins Park, Pa., assignor to Samuel L. Cohn and Charles C. Cohn, copartners, doing business as Colonial Alloys Company, Philadelphia, Pa.

Application April 24, 1946, Serial No. 664,581

4 Claims. 1

This invention relates to methods and apparatus for the electrolytic treatment of elements of slide fasteners of the zipper type, the treatment referred to including electroplating, anodizing of aluminum elements or the like.

From the following description, it will be evident that the invention is applicable to the electrolytic treatment of such fasteners in general, but to simplify the description, stress will be particularly laid on the anodizing of aluminum or aluminum alloy elements, the handling of the elements evidently being applicable to treatment such as plating.

The elements of so-called zippers are frequently exposed to view and proper appearance is of considerable importance. Frequently, particularly in womens wear, the metallic appearance of these elements as made from metal without further treatment is not desired. Accordingly, the elements have sometimes been enameled in colors, but such enameling does little more than sell the zipper because after very little wear the enamel is worn off by the contact of the slide and an even more unsightly result occurs than would be the case if the zipper elements were untreated.

Attempts to treat the zipper elements separately in electrolytic fashion are quite unsatisfactory because of their small size as is also any attempt to treat the wire stock from which they are formed because in the formation of the zippers such distortion of the metal occurs as would damage the surfaces. Accordingly, numerous proposals have been advanced for the electrolytic treatment of the elements after assembly upon their supporting tapes. The proposals which have been made are generally unsatisfactory involving complications in formation of the zipper tapes such as incorporation of conducting threads, foils or the like. Furthermore, the methods heretofore proposed have a common failure in that an individual element in a group may, for some reason, not make good contact with the conductor associated with the tape and under such circumstances will not be electrolytically treated and will stand out very noticeably as a visible defect.

In accordance with the present invention, there are provided a method of treatment and apparatus therefor which are found to give excellent results in both plating of the zipper elements and anodizing of aluminum or aluminum alloy elements, which latter will be hereafter referred to generally as aluminum elements. The anodizing treatment is particularly valuable be- 2 cause the oxide coating which is produced is capable of absorbing or adsorbing dyes whereby almost any desired color can be secured. The colors thus produced, in particular, may be of metallic appearance and excellent simulation of gold, platinum or silver may be secured as well as practically any other desired color having either a metallic luster or a matte appearance. Furthermore, these colored anodized coatings, or even uncolored coatings used merely for purposes of protection against corrosion, are extremely hard and the sliding engagement with the zipper elements of the slide in closing and opening operations produces no appreciable wear over a long period of time. Accordingly, from the standpoint of securing the maximum results in the way of appearance, anodizing followed by coloring is a most desirable procedure. To secure proper anodizing, it is necessary that perfect electrical contact be assured between the zipper elements and the source of current, otherwise the anodizing may fail at certain points or may not be uniform with a resulting non-uniformity in depth or brilliance of color or appearance.

A further advantage of anodic treatment of the elements is that the tape, usually of cotton, may be dyed simultaneously with the anodic coating by the use of dyes suitable for both purposes. On the other hand, by the use of dyes which will not color cotton but will color the anodic coating, the coating may be colored and sealed and then the cotton tape may be separately dyed in a different shade or contrasting color.

In accordance with the preferred embodiment of the invention, the electrolytic treatment is carried out on a pair of tapes, the zipper elements of which are interlocked. This is of particular advantage because, at the present time, the manufacture of zippers generally involves the formation of the zippers in this fashion, i. e., at the time of application to the tapes, the zipper elements are interlocked so that a closed zipper is the direct result of the manufacturing operation. It is obviously of advantage to apply the electrolytic operation directly to the closed zipper which then requires no further manipulation to place it on the market.

A further object of the invention is to provide for the electrolytic treatment without requiring any special steps in the manufacture of the zipper.

The foregoing and other objects of the invention, particularly relating to details of manipulation and apparatus, will become apparent from the following description read in conjunction with the accompanying drawing, in which:

Figure l is a fragmentary perspective view showing a rack for the support of zipper strips for electrolytic treatment;

Figure 2 is a fragmentary transverse sectional view showing the assembly of rack elements and the fashion in which the zipper strips are held thereby; and,

Figure 3 is a perspective view indicating the fashion in which zipper strips may be treated in accordance with a modified form of the invention.

In the case of a closed zipper, it might appear that all of the zipper elements are in serial contact and that, consequently, it would be possible to secure electrical connection with all of the elements by connection with an electrical current source at one end of the strip. In fact, however, this is not the case at least to the extent of providing sufficiently good electrical contact to insure the proper carrying of current with substantially negligible resistance through any considerable length of the strips. In particular, anodizing of aluminum zipper elements requires relatively heavy currents and the resistance, due to poor contacts, would cause a very rapid falling off of voltage along the zipper. In accordance with the present invention, it has been discovered that, despite the poor contacts which are afforded in a straight zipper, excellent contacts may be secured if the zipper is substantially continuously subjected to bending with small radius of curvature serving to force the zipper elements against each other. Preferably, the zipper is caused to assume a sinuous form under such stresses producing the waves that the zipper elements are brought into tight engagement with each other. When this is done and the zipper is, for example, wound in and out through the teeth of a coarse comb, it is found that such excellent contact is secured that very little resistance is introduced in a length of many inches of the zipper so that electrical contact at one end will provide a sub-' stantially constant potential through the zipper and consequent even distribution of current density. Preferably, however, the introduction of current is effected at short intervals along the length of the zipper to insure the highest degree of uniformity of treatment. If the contacts made with the zipper elements are afforded by pointed or sharp edged'devices, the contact points, when miscroscopically examined, will appear untreated; nevertheless, from the standpoint of ordinary Viewing when the zipper is used they will not be at all apparent. The result, accordingly, is for practical purposes a complete uniform treatment.

While in accordance with the above, the sinuous configuration of the zipper may be secured in various fashions, there will be described, as an illustration of the invention, a preferred mode of handling the zippers for treatment. To simplify the discussion, reference will be made particularly to such apparatus and procedure as is involved in the anodizing of aluminum elements, it being obvious to those skilled in the art that electroplating or other treatment may be efiected in substantially identical fashion.

Referring to Figure 1, there is illustrate therein a rack for the support of zippers, this rack comprising runners 2 which may be of aluminum or aluminum alloy between which are secured slats 4 having sharp edges such as indicated at 6. These racks may be of any desired size depending upon the vessel available for the treat- (1715 ment and the sizes of zipper strips which are to be treated. The uppermost and lowermost slats indicated at 8 are of slightly diiierent form, being provided not only with edges l0 corresponding to the edges =6 of the other slats but also with upright portions [2 providing sharp edges l4.

The zipper strips, consisting of a pair of tapes and their interlocked fastener elements, the tapes being indicated at T and T and the elements being indicated at E, are wrapped about the frames in spiral fashion as indicated in Figure 1, the ends of the tapes being clamped or otherwise secured in a fashion which need not be described. Generally speaking, the tapes as they come from the manufacturing machine contain lengths of interlocking elements, for example, of the order of nine inches in length containing about two hundred and fifty elements with interspersed regions of the tapes from which the elements are absent, severance through such regions serving to provide tape lengths for attachment of the zippers. In accordance with the invention, the tapes, with or without such interruptions of the elements, are wound about the frames as indicated.

The frames thus carrying the tapes are then stacked as indicated in Figure 2 with intermediate frames consisting of runners l6 and sharp edged slats l8 positioned so as to be intermediate with the slats of the frames on which the zippers are wound. By such association of the frames, a sandwich arrangement is built of any desired number of frames so that, as indicated in Figure 2, when the frames are clamped together, the zippers are caused to take on sinuous configurations by which curvatures of small radius are imported thereto with consequent assurance that all of the zipper elements are in tight engagement with each other. The fashion in which the sinuous condition is maintained even at the ends of the frames will be evident from Figure 2 in which the cooperation of the slats I8 of the intermediate frames with the end slats of the supporting frames will be evident.

The assembly thus provided not only insures continuous serial contacts between the zipper elements but local contacts therewith to insure further that a continuous electrically conductive configuration will result. As will be evident from Figure 2, the contacts of the zipper elements with the slats are substantially only point contacts and even though these contact points remain untreated, they will be entirely unnoticeable in the final result.

While direct current anodizing is possible, it is preferable to use alternating current anodizing in which two similar assemblies of frames and supported zippers are used as the electrodes in both terminals in the anodizing tank. It has been found particularly advantageous to use alternating current anodizing in one of the usual acid electrolytes because it has been found that when alternating current is used the cotton tape does not appear to be deteriorated by the acid as is sometimes the case if a strongly acid electrolyte is used in direct current anodizing. This may possibly be due to the fact that in alternating current anodizing, since each pole is alternately positive and negative at the frequency of the alternating current supply, hydrogen is liberated, which, being absorbed in the tape, may form an atmosphere protecting the tape against the effect of the acid. While this is a possible explanation of the protection, it will be under stood that this explanation is merely offered as a suggestion and while protection of the tape is afforded, the reason therefor is not known with certainty.

It may be noted that the configuration which is provided permits the free escape of hydrogen which is important in alternating current anohydrogen which may blank off from the anodizing action certain portions of the elements.

The anodizing procedure may be carried out at temperatures and for periods which are conventional in the art and since the conditions of treatment form no part of the present invention, they need not be described in detail. During the anodizing, the racks themselves, if made of aluminum, are, of course, anodized since they are formed of aluminum or aluminum alloy.

When the anodizing is completed, it may be followed by the conventional rinsing, whereupon the assembled racks and tapes may be handled as a unit through any subsequent steps. If dyeing is to be effected, they are treated in suitable dye baths, as well known in the art, followed by rinsing and sealing. If dyes are used which are not only absorbable or adsorbable in the oxide coating but are also adapted to dye the tapes, the final result will be colored zipper elements carried by the dyed tapes. On the other hand, if it is not desired to dye the zipper elements and the tapes simultaneously, there may be first used dyes which will color the zipper elements without coloring the tapes. After sealing, the zippers, still carried by the frames, may then be immersed in suitable dyes for the tapes. Once the zipper elements are sealed, they will no longer absorb dye, and, consequently, the tapes may be dyed with colors differing from the colors of the zippers. The particular dyes which may be used are well known to the art in both the fields of dyeing of anodic coatings and of dyeing cotton or other tape fabrics.

As examples of dyes which will simultaneously color the anodic coatings and dye cotton tapes there may be mentioned chlorantine fast blue GLN, chlorantine fast yellow B, chloramine sky blue A, Congo red, and diamine orange BA. As examples of dyes which will color the anodic coatings but will not dye cotton tape there may be cited cloth fast blue GN, croceine scarlet MOO, comacid fast red B, chrome fast blue GR, chromate brown R, and chromaven green G. Numerous other dyes in both classes will be apparent to those skilled in the art.

After the various foregoing treatments, the frames may be disassembled and the zippers removed, having been dried on the frames if desired. Since, in the above treatments, they have been mechanically unaffected, they may be immediately reeled for sale or use. Priorto the next use of the frames, if made of aluminum, they are, of course, stripped in conventional fashion so as to re-expose the metal to make contact with subsequently treated zippers.

From the foregoing, it will be clear that an arrangement is provided whereby the zipper elements are maintained in tight contact so that continuous electrical conductivity is insured even if the zippers become anodized. The anodic coating offers a high electrical resistance after sealing and even a substantial resistance is built up before sealing during the anodizing. When the elements are in tight contact, however, the anodizing cannot take place at the points of contact, and, consequently, the conduction of the electrical circuit is not interrupted. It may be noted that these contacts between the elements are on their adjacent surfaces, which, in the final zipper, are substantially invisible even when the zipper is opened. Consequently, the fact that anodizing does not take place at the points of contact is immaterial. Actually, the areas of contact are very small and the final zipper, whether opened or unopened, presents a substantially uniform appearance.

While the sinuous or zigzag condition of the zipper, as described above, is desirable, produced, for example, by interlacing the zipper between the teeth of a comb-like support, it has been found that quite satisfactory results are also attainable in a different fashion. In accordance with a further modification of the invention, there is provided a support consisting of a cylinder 20 of metal or wood covered with a rubber sheath 22, which, in turn, is surrounded by a screen 24, which, for the purpose of anodizing, would be of aluminum or aluminum alloy. This screen is desirably of fine mesh and so woven that the wires thereof running in one direction are curved in and out to a maximum extent between the wires running in the other direction presenting, accordingly, outwardly directed peaks of minimum radius of curvature. About this mesh, there is helically wound the zipper tape or tapes indicated at T", this modification of the invention being adapted for the treatment of zippers comprising two tapes and interlocking fastener elements or for the treatment of single tapes containing the elements of only one side of the zapper, which elements do not make contact with each other. In either case, each element will contact tightly the wire mesh, this being the result of wrapping the tape or tapes tightly upon the mesh, the resilience of the rubber sheath 22 permitting tight contacts to be attained and maintained The wound cylinders thus provided may be connected to the poles of an anodizing vat and anodizing, rinsing, dyeing and sealing may be carried out in conventional fashion. The use of the wire mesh provides point contacts, and, consequently, as in the previously described modification of the invention, there are only minute unnoticeable areas which are not anodized. The wire mesh, furthermore, permits the free escape of hydrogen in alternating current anodizing so that this gas does not interfere with the continuity of the anodic coating.

From the above, it will be evident that, in connection with both modifications, there are provided electrical contacts which are suitable for electrolytic treatments in general, including plating. Since plating or other electrolytic treatments may be carried out in their respective conventional fashions, aside from the contact configurations involved, it will not be necessary to describe them in detail.

It will be clear from the foregoing that variations in the procedures and apparatus adapted may be made, as will be apparent to those skilled in the art, without departing from the invention as defined in the following claims.

What I claim and desire to protect by Letters Patent is:

1. Apparatus for the electrolytic treatment of zippers comprising a metallic frame including a series of elongated members extending in substantial parallelism to provide a lattice about which a closed zipper may be wound, and a second separate metallic frame including a series of elongated members extending in substantial parallelism to provide a lattice, the members of the second frame being constructed and arranged to project between the members of the first mentioned frame when the frames are assembled with the members of the two lattices in substantial parallelism to provide a sinuous configuration of the zipper to produce a stressed engagement between the metal elements thereof.

2. Apparatus for the electrolytic treatment of zippers comprising a metallic frame including a series of elongated members extending in substantial parallelism to provide a lattice on at least one surface of which a closed zipper may I be located, and a second separate metallic frame including a series of elongated members extending in substantial parallelism to provide a lattice, the members of the second frame being constructed and arranged to project between the members of the first mentioned frame when the frames are assembled with the members of the two lattices in substantial parallelism to provide a sinuous configuration of the zipper to produce a stressed engagement between the metal elements thereof.

3. The method of electrolytically coating closed zippers formed of metal elements clamped on non-conducting carriers comprising winding a closed zipper about a metallic frame including a series of elongated members extending in substantial parallelism to provide a lattice, the zipper extending transversely across said elongated members, associating with said frame a second separate metallic frame including a series of elongated members extending in substantial parallelism to provide a lattice so that the members of the second frame project between the members of the first mentioned frame and impart to the closed zipper a sinuous configuration to produce a stressed engagement between the metal elements thereof, and subjecting the resulting assembly to an electrolytic action involving current conduction through the series of 8 metal elements and thereby coating the metal elements of the zipper.

4. The method of electrolytically coating closed zippers formed of metal elements clamped on non-conducting carriers comprising locating a closed zipper across at least one face of a metallic frame including a series of elongated members extending in substantial parallelism to provide a lattice, the zipper extending transversely across said elongated members, associating with said frame a second separate metallic frame including a series of elongated members extending in substantial parallelism to provide a lattice so that the members of the second frame project between the members of the first mentioned frame and impart to the closed zipper a sinuous configuration to produce a stressed engagement between the metal elements thereof, and subjecting the resulting assembly to an electrolytic action involving current conduction through the series of metal elements and thereby coating the metal elements of the zipper.

CHARLES C. COHN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

3. THE METHOD OF ELECTROLYTICALLY COATING CLOSED ZIPOPERS FORMED OF METAL ELEMENTS CLAMPED ON NON-CONDUCTING CARRIERS COMPRISING WINDING A CLOSED ZIPPER ABOUT A METALLIC FRAME INCLUDING A SERIES OF ELONGATED MEMBERS EXTENDING IN SUBSTANTIAL PARALLELISM TO PROVIDE A LATTICE, THE ZIPPER EXTENDING TRANSVERSELY ACROSS SAID ELONGATED MEMBERS, ASSOCIATING WITH SAID FRAME A SECOND SEPARATE METALLIC FRAME INCLUDING A SERIES OF ELONGATED MEMBERS EXTENDING IN SUBSTANTIAL PARALLELISM TO PROVIDE A LATTICE SO THAT THE MEMBERS OF THE SECOND FRAME PROJECT BETWEEN THE MEMBERS OF THE FIRST MENTIONED FRAME AND IMPART TO THE CLOSED ZIPPER A SINUOUS CONFIGURATION TO PRODUCE A STRESSED ENGAGEMENT BETWEEN THE METAL ELEMENTS THEREOF, AND SUBJECTING THE RESULTING ASSEMBLY TO AN ELECTROLY-TIC ACTION INVOLVING CURRENT CONDUCTION THROUGH THE SERIES OF METAL ELEMENTS AND THEREBY COATING THE METAL ELEMENTS OF THE ZIPPER. 